I wonder though...would they want to staff a 3rd Epcot entrance - just for one resort?
Right - there's the issue. However, if it sells DVC points, then maybe. Realizing the DVC dues would essentially have to pay for it. Nothing DVC does comes back to the resort, everything after the initial construction is paid by the annual dues. That's the reason the resorts are often piggybacked onto the existing resorts - it reduces the cost of infrastructure. Things such as housekeeping/laundry instead of having to have their own they can share facilities with the resorts. The owners then pay for their portion of the operation. It actually is a win for the resorts too as it likely reduces expenses.
If a third entrance was for the DVC resort only, it would have to be fully funded by DVC. If they allowed CBR guests to use it, then it would be partly DVC funded, and partly resort funded.
Disney is in an interesting position with DVC. The last non-monorail resort to go on sale was Animal Kingdom Villas - which opened around $104 a point in 2007. BLT opened at $112 a point in 2009. Between 2009 and 2014 (6 years) DVC prices skyrocketed from $112 to $160 per point (a 43 % increase in 6 years). Put in that time they are primarily selling BLT, VGF and then the Poly, which are extremely desirable locations. (Probably most desirable.) In addition, they make the rooms more expensive (# of points per night) making the costs much, much higher, and of course the profits.
Even so, the Poly has sold somewhat slower than expected. Not badly, just not as fast as they thought.
Now they are moving to a less desirable location - Wilderness Lodge. Sure it is fairly easy access to MK, but it's not a monorail resort. Will they lower the price? Unlikely. However, they will likely have to have a lower point per night number, making it less profitable.
Then we come to CBR. With no entrance to Epcot - CBR is not much different than SSR or OKW or AKV. No direct park access. By 2019 you are likely looking at a $190 per point price point. How do you sell that to people? At the Poly you can say "Look at what you are saving versus a $700 a night hotel room." Building next to CBR, suddenly you are comparing to a $200 per night hotel room? So, do you make the resort cheaper? Or do you add perceived value to the resort in some way to make it better than CBR? This can be done but only in two ways (1) improved amenities or (2) direct access to park. Without these two things - selling this resort will be a quite difficult sell, UNLESS Disney decides to start a new 2nd tier DVC - a complicated decision.
Sorry to go on so long, but I find this whole thing very fascinating with exactly what's going to happen.